Turn in 2.3.1 Feedback Loop & completed Conclusion ?s Keep Part III Body Graphic Organizer for 2.3.2 Endocrine System PPT Activity 2.3.2 Hormones Gone Wild Pt. 1 Groups of 4=Maniken Partner & Pair up with another Group

Pineal Parathyroid Pancreas Pituitary Adrenal Thyroid Thymus Ovaries Testes 10. Hypothalamus

THE ENDOCRINE SYSTEM

What is the Endocrine System? Communication system for the body Secretes hormones – chemical messengers These hormones regulation of growth, metabolism, sexual development, and emotions Internal balance of body systems = homeostasis by working with the nervous system Specifically the hypothalamus

Endocrine Glands Ductless Meaning: the hormone that is secreted goes into the blood stream directly to a target cell/tissue. Major Endocrine Glands Pituitary Gland Hypothalamus Thymus Pineal Gland Testes Ovaries Thyroid Parathyroid Adrenal Glands Pancreas

Exocrine Glands They have ducts carries secretions to external locations of the body Examples sweat glands salivary glands mammary glands stomach liver pancreas

Hormones HORMONES are chemical MESSENGERS that act on target cells or organs.

Classes of Hormones Steroid Hormones Amino Acid Derivative Hormones Sex hormones – lipids made from cholesterol Testosterone, Estrogen Amino Acid Derivative Hormones Derived from amino acids – tyrosine and tryptophan Epinephrine Peptide Hormones Made of chains of amino acids Most numerous Insulin Growth Hormone

Target Cells and Receptors Target cells receive hormone (it binds to the cell membrane and enters the cell after it is recognized) and initiate a specific response.

FYI… Activity Information Endocrine action: the hormone is distributed in blood and binds to distant target cells. Paracrine action: the hormone acts locally by diffusing from its source to target cells in the neighborhood. Autocrine action: the hormone acts on the same cell that produced it.

Endocrine Versus Nervous Enable cells to communicate with others by using chemical messengers. Endocrine system is slower than the nervous system because hormones must travel through the circulatory system to reach their target.

Nerve impulse Neuron transmits nerve impulse Neurotransmitter Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Nerve impulse Neuron transmits nerve impulse Neurotransmitter released into synapse Post- synaptic cell responds (a) Target cells (cells with hormone receptors) respond to hormone Glandular cells secrete hormone into bloodstream Bloodstream Hormones have no effect on other cells (b) 14

Major Hormones

Pituitary Gland Often called the “master gland” Controlled by the hypothalamus in the brain Base of brain Anterior and posterior pituitary lobes

Anterior Pituitary Hormone Growth hormone (GH)- stimulates growth in childhood and is important for maintaining a healthy body composition Problems with GH can result in too little growth or too much growth

The Alton Giant Dwarfism

Thyroid Gland The thyroid hormones control your metabolism Thyroxin (T4) & Tri- iodothyronine (T3) - both increase the rate at which cells release energy from carbohydrates Calcitonin – regulates calcium in blood

Parathyroid Gland Four tiny glands that help maintain calcium and phosphate levels Parathyroid Hormone (PTH) - takes calcium from the bones to make it available in the blood

Adrenal Gland Each adrenal gland is actually an organ located right on top of each kidney Outer portion called adrenal cortex Inner portion called adrenal medulla

Adrenal Cortex Aldosterone – a mineralcorticoid, helps kidneys conserve sodium and excrete potassium, maintaining blood pressure Cortisol – glucocortoid, keeps blood glucose levels stable Adrenal Sex Hormones - androgens (male) and estrogens (female)

Pancreas Large gland behind your stomach that helps the body to maintain healthy blood sugar (glucose) levels Contains islands of cells called the Islets of Langerhans, which secrete glucagon and insulin

Pancreas Insulin- secreted when the blood sugar level is high Glucogen- secreted when the blood sugar level is low Both work together to keep blood sugar levels balanced

Pineal Gland located between the cerebral hemispheres secretes melatonin- important for maintaining Circadian rhythms (light and dark activity)

Thymus Gland large in young children, gradually shrinks with age secretes thymosins- important to immune function

Reproductive Gland Ovaries- estrogen progesterone Testes- testosterone

How Do We Maintain Homeostasis? We maintain it with FEEDBACK LOOPS We have receptors throughout our bodies; when levels are out of homeostasis; feedback loops are activated. Mostly NEGATIVE FEEDBACK loops

There are 2 Types of Feedback: Negative and Positive Negative Feedback - is called negative due to the fact that you are doing the OPPOSITE process. For example, if you body temperature is too high..negative feedback causes the temperature to DECREASE . Positive Feedback is a cascade and there is an increase in effect.

Negative Feedback Mechanisms The net effect of the response to the stimulus is the SHUT OFF the original stimulus OR reduce its intensity.

Why This is Negative Feedback Beta Cells of Pancreas Release insulin in response to high sugar Ultimately the INSULIN is turned off when sugar level returns to normal

Positive Feedback The initial stimulus does NOT cause a switch to be “shut off”. Rather, a CASCADE of more ON switches in response to the initial response occurs. Examples: Giving Birth and Blood Clotting

Positive Feedback: BIRTH Cervix Dilates ( Initial STIMULUS) Stimulates stretch receptors in cervix These receptors stimulate Hypothamus (gland in brain) Hypothamus “tells” posterior pituitary to release oxytocin. Oxytocin acts on uterine muscles causing them to contract. Muscle contractions force baby through cervix, stretching it. (REINFORCES ORIGINAL STIMULUS)

Homeostatic Control Mechanisms Negative feedback summary: Prevents sudden, severe changes in the body Reduces the actions of the effectors Corrects the set point Causes opposite of bodily disruption to occur, i.e. the ‘negative’ Limits chaos in the body by creating stability Most common type of feedback loop Examples: body temperature, blood pressure & glucose regulation

Homeostatic Control Mechanisms Positive feedback summary: Increases (accelerates) the actions of the body Produces more instability in the body Produces more chaos in the body There are only a few types necessary for our survival Positive feedback mechanisms are short-lived Controls only infrequent events that do not require continuous adjustments Considered to be the uncommon loop Examples: blood clotting and child birth